1. Field of the Invention
The present invention relates to an endoscope apparatus and specifically relates to an endoscope apparatus that can display a blood vessel in an inner portion of a subject.
2. Description of the Related Art
Conventionally, in a medical field, various less-invasive examinations and surgical operations using endoscopes have been performed. A surgeon can insert an endoscope into a body cavity to observe an image of an object picked up by an image pickup apparatus provided in a distal end portion of an insertion portion of the endoscope and as necessary, perform a treatment of a lesion site using a treatment instrument inserted through the inside of a treatment instrument channel. The surgical operations using endoscopes eliminate the need for, e.g., laparotomy, and thus, provide the advantage of reducing a physical burden on patients.
An endoscope apparatus includes an endoscope, an image processing apparatus connected to the endoscope, and an observation monitor. An image of a lesion site is picked up by an image pickup device provided in a distal end portion of an insertion portion of the endoscope, and the image is displayed on the monitor. A surgeon can perform diagnosis or a necessary treatment while viewing the image displayed on the monitor.
Also, examples of the endoscope apparatuses include those that enable not only normal light observation using white light, but also special-light observation using special light such as infrared light in order to observe blood vessels in inner portions.
In the case of infrared endoscope apparatuses, for example, indocyanine green (ICG) having the characteristic of having an absorption peak in a region of near-infrared light with wavelengths of around 805 nm is injected into the blood of a patient as a medical agent. Then, infrared light with wavelengths of around 805 nm and infrared light with wavelengths of around 930 nm are irradiated to an object in a time division manner from a light source apparatus. A signal of an image of the object picked up by a CCD is inputted to a processor in the infrared endoscope apparatus. For example, as disclosed in Japanese Patent Application Laid-Open Publication No. 2000-41942, as such infrared endoscope apparatuses, those in which a processor assigns an image with wavelengths of around 805 nm to a green signal (G) and an image with wavelengths of around 930 nm to a blue signal (B) and outputs the signals to a monitor are proposed. Since an image of infrared light with image of around 805 nm, which is well absorbed by ICG, is assigned to green, a surgeon can observe an infrared image with good contrast when ICG administration is performed.
For example, in an endoscopic submucosal dissection (ESD) in which a submucosal layer in which a lesion site exists is dissected and removed using an endoscope, in order to prevent relatively thick blood vessels in a mucous membrane from being cut by, e.g., an electrosurgical knife, a surgeon performs a treatment such as dissection after confirming the positions of such blood vessels. Blood vessels that may cause heavy bleeding run from a submucosal layer to an intrinsic muscle layer.